We present the dynamics of the liquid viscosity and of the liquid bath depth: it can be shown that the dominant wavelength is smaller with higher fields but differs if the liquid film is thick or thin, inviscid or viscous. The development of the pattern involves nonlinear interactions. While a stable deformed interface has been observed on the analogous case of a magnetic fluid under magnetic fiel...
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A new explanation of the `total voltage effect' is offered. It is based on the mechanism of vacuum breakdown proposed earlier. According to this mechanism, the vacuum breakdown at an electric field of 10 MV/m is caused by the ionisation process in the gas desorbed from the pores and cracks in the negative electrode surface. It has been found that the larger the distance between the electrodes, the...
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The present paper gives a description of the metal-dielectric cathode interaction. There is an explosive electron emission on the cathodes, that occurs through explosions of the metal microprotrusions at so-called triple points (metal-dielectric vacuum). The current of a vacuum discharge over the dielectric surface plays an initiating role. Such a mechanism of emission operates in low-voltage ferr...
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This paper described the discharge classification under nonuniform electric field in air and He at low gas pressures for the application of HV technology to the power apparatus in space. In order to discuss quantitatively the change of the discharge, an image processing method was introduced. In the first place, four shape parameters were proposed to characterize the discharge pattern: the area S View full abstract»

An intensified high-speed imaging technique was used to observe the optical events associated with the pulsed-field breakdown of an alumina ceramic tube having two concentric planar electrodes metalized onto its end face. HV pulses, typically of 5 kV amplitude (5 kV μs -1 rate of rise), were applied to the radial MIM insulator-electrode regime under ultrahigh vacuum (pressure <5&t...
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A method for preliminary treatment of electrodes by a microsecond low-energy intense electron beam is proposed. It has been demonstrated that such a beam melts off the electrode surface and cleans the surface layers from impurities and dissolved gases. In combination with subsequent conditioning of the vacuum gap with low-current pulsed discharges, high breakdown electric fields can be attained
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In the original paper (see ibid., vol. 1, no. 1, p. 153-9, 1994), the authors show that the two-parameter Weibull distribution is satisfactory to represent the results on samples of HV thermally aged EPR cables. This does not exclude, as well as they indicate it, that the three-parameter Weibull distribution is sometimes justified, especially in the case of results of short term dielectric breakdo...
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Investigations of fault are propagation on spacecraft cables under specific conditions, e.g. vacuum, normal and oxygen enriched atmospheres have been performed. Typical patterns of fault arc extinction have been identified and their consequences with respect to causes of damages are discussed. The results indicate that for a given test current and test voltage the behavior of the arc and the damag...
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The results of experimental and theoretical investigations of high-current-density field emission from nanometer objects on the tungsten cathode surface are presented. Such objects were microprotuberances, and spots of Zr or ZrO, produced by a thermal-field buildup process (microtips) and selective adsorption (spots). The limiting values of stable emission current densities from local areas of the...
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The paper presents the results of investigations of the electric strength at 50 Hz AC voltage of vacuum insulation systems that were not subjected to conditioning. The experiments have shown that a Co-Mo alloy coating electrolytically deposited on the surface of copper electrodes causes, at the pressure 2 mPa, >25% increase of electric strength of unconditioned vacuum insulation systems. This b...
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The reduction of costs, the enhancement of lifetime of tubes and the search for environmentally friendly processes and materials gave the main impact for research and development efforts within the last years for power grid electron tubes. Physical and chemical effects are discussed that determine the performance of todays devices. New material compositions are reported for directly heated cathode...
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The multipactor and flashover phenomena of alumina rf windows used in a high-power klystron have been investigated. Multipactoring due to the high yield of secondary electron emission takes place during rf operation. A spectrum analysis of luminescence due to multipactoring shows that multipactor electron bombardment causes F centers in alumina, thus leading to surface melting. From the results of...
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The pressure of vacuum switching elements after production is checked normally by Penning or magnetron methods (combined electrical and magnetic field). Vacuum in the range of 10-1 to 10-4 Pa can be measured in this way. After assembly into circuit breakers however, these methods are not applicable. HF interruption performance during the make operation was proposed earlier a...
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The initiation and sustaining of field emission processes from a liquid surface are based mainly on the effect of field amplification at the surface microtips. Such microtips form under different types of hydrodynamic instabilities. However, the threshold field of such instabilities has a very high value. At the same time, there are some situations when one needs to excite the emission using an ar...
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Investigations have been carried out on right cylindrical Teflon spacers in vacuum under dc stress to study the effect of cathode geometry on surface charging and flashover. Three cathode support arrangements were used. Type 1 involved a recess in the cathode into which the spacer was located, type 2 was a simple flat plate cathode, while type 3 had a raised insert on the cathode surface over whic...
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Results are presented of investigations of the pulsed electric strength and threshold current densities of YBa2Cu3O7 and Nb cathodes at cryogenic temperatures. It has been shown that the cooling of a Nb cathode from 300 to 4.2 K leads to a 1.5 to 2.5× increase of pulsed electric strength and that the transition of the cathode from the normal to the supercondu...
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We discuss a number of practical implications from recent studies on HVDC design concepts for vacuum components. These studies dealt with microwave tube technology. The conclusions, however, are valid for a wide range of components. The goal of this work is to provide a scientific basis for the design of HVDC vacuum components. From a study of breakdown and emission mechanisms, and from the measur...
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Temporal change in electric field strength at the insulator-cathode-vacuum interface accompanied by charging of the insulator have been studied by using a two-dimensional Monte Carlo simulation. The study employed cylindrical and conical insulators. Each of the insulators was made of PMMA, polyimide or Al2O3 . The field strength with cylindrical insulators shows an abrupt inc...
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The paper describes the results of a direct experimental observation of the development of an electrohydrodynamic instability at an explosive-emission liquid-metal cathode along with a theoretical analysis of the growth and destruction of the protrusion formed on the cathode surface
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Current plans for the development of an established manned base on the surface of the Moon will require power levels from 100 kW up to 1 MW. Voltage levels for transmission will likely approach 10 kV, with distances between sources and loads of up to 5 km. Vacuum insulation is being considered due to its simple and low mass design. In this paper we discuss the problems in implementing large scale ...
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Threshold characteristics of pulsed dielectric breakdown in vacuum, obtained at various experimental conditions, are considered in detail. As would be expected, the breakdown time delay τd (supposing τd<τp, the microwave pulse duration) depends on many initial parameters, such as the microwave intensity J, the nature of the irradiated material and it...
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Using three types of copper electrodes with different surface areas, experiments were performed to investigate the influence of electrode area on the conditioning effect,which is a characteristic of dielectric breakdown in vacuum gaps. The conditioning process varied with electrode area: the smaller the electrode area, the sooner conditioning ended. Breakdown voltages after completion of condition...
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Aims & Scope

IEEE Transactions on Dielectrics and Electrical Insulation contains topics that are concerned with dielectric phenomena and measurements, with development and characterization of gaseous, vacuum, liquid and solid electrical insulating materials and systems; and with utilization of these materials in circuits and systems under condition of use.